Dynamometer for well pumps



a o i a 1 c-noss REFERENCE SEARCH 800 March 10, 1970 J. WENISCH3,499,324

DYNAMOMETER FOR WELL PUMPS Filed Dec. 14, 1966 3 Sheets-Sheet 1ATTORNEYS March 10, 1970 J. WENISCH DYNAMOMETER FOR WELL PUMPS 3Sheets-Sheet 2 Filed Dec. 14, 1966 PRESSURE RECORDING MEANS March 10,1970 J. WENISCH 3,499,324

DYNAMOMETER FOR WELL PUMPS Filed Dec. 14, 1966 3 Sheets-Sheet 5 FIG.4

INVENT OR Josef \A/entsch ATTORNEYS US. Cl. 73-141 3 Claims ABSTRACT OFTHE DISCLOSURE A low-pressure, high-displacement pump is connected to acylinder 'for quickly and easily moving a piston into engagement withthe force transmission path of a deep well pump. A second high-pressure,low-displacement pump is also connected to the cylinder and once thepiston is brought into engagement, the second pump causes the piston tosupport the weight of the pump rod, so that the weight of the rod canquickly be determined.

Dynamometers for Well pumps serve the purpose of determining whether apump located at great depth is working properly by measuring the forcetransmitted to the pump rod. For this purpose the dynamometer must beinterpositioned in the transmission path of the driving force to thewell pump. Existing arrangements are adapted for temporarily interposinga dynamometer between the head of the polish rod and thecross-headfdepending from the so called horse head, so that the desiredmeasurements can be effected.

The invention herein is related to a dynamometer for well pumps which isprovided with a hydraulic pistoncylinder arrangement, which is adaptedfor being linked into the force transmission path of the pump rodbetween the upper end of said pump rod and the suspension means thereof,whereby said piston and cylinder 'lare brought into the operatingposition by a main pump and, in the operating position, the pump rod isvia the hydraulic'pistoncylinder-arrangement connected with itssuspension means. For interpositioning the hydraulicpiston-cylinderarrangement into the force transmission path it isnecessary to lift the upper end of the pump rod from its suspensionmeans with the aid of said piston-cylindernrrangement. Prior to thislifting it is necessary to bring the dynamometer into contact with theupper end of the pump rod and its suspension means and this in turnmakes it necessary to overcome a certain amount of dead-stroke. Thearrangement according to the invention is especially suitable forrapidly elfecting said dead-stroke.

An embodiment of the dynamometer according to the invention isschematically illustrated. FIGURE l shows the overall construction,FIGURE 2 shows the suspension of the head of the polish rod on the crosshead, FIGURE 3 is for the purpose of illustrating the interposition ofthe dynamometer and FIGURE 4 is a side cross-sectional view of thespring pre-tensioning means for levers 20 and 21.

In the arrangement according to FIGURE 1 on the post 1 a beam 2 ispivotally supported at axis 3. There is further provided a counterweight4, a motor 5 together with a crank mechanism and the connecting rod 6.On the so called horse-head 7 there are attached two ropes 8, which areconnected by a cross-head 9. From this cross niged States Patent 03,499,324 Patented Mar. 10, 1970 ice,

As is shown in FIGURE 2 the polish rod 10 rests on a plate 13 of thecross-head 9 with its thickened head 12. This thickened head 12 isprovided with a cross-head 14 which is given a cylindrical bottom face15.

In FIGURE 3, the essential parts of the piston-cylinderarrangement ofthe dynamometer are illustrated, which parts are arranged within ahousing not shown. The dynamometer is interpositioned between thecross-head 14 and plate 13, whereby the dynamometer is inserted byswivelling it approximately around the axis of the cylindrical bottomface of cross-head 14. When inserting the dynamometer the cross-head 14must be lifted, requiring the expenditure of a large amount of energy.The dynamometer is secured in its position only when thepistoncylinder-arrangement 16, 17 is in engagement between the plate 13and the cross-head 14. For rapidly securing said engaged position alow-pressure cylinder 18 together with a piston is provided. The pistonrod-19 of saidcylinder is acted upon by a spring (see FIGURE 4), whichis pretensioned by a lever 20. When the piston-cylinderarrangement 16,17 is in its correct position between the plate 13 and the cross-head 14a disengaging lever 21 is actuated, which in turn releases the pistonrod 19. By the pressure exerted by the spring, the piston within thecylinder 18 is forced in lefthand direction and supplies to both of thecylinders 17 such a pressure that the piston-cylinder-arrangement 16, 17is clamped between the plate 13 and the cross-head 14. This pressurethereby is supplied via conduits 22, 23 which are provided with backpressure valves 24, 25. With the pressure-cylinder-arrangement 16, 17being clamped in its position the dynamometer is not yet linked into thetransmission path for the head 9 the polish rod 10 is depending. Thewell casing forces from the motor to the polish rod because the pressurewithin the low pressure cylinder 18 is insufiicient for bringing thehead 12 of the polish rod out of contact with the plate 13. For thispurpose a high pressure cylinder 26 is provided, the piston of which isactuated via its piston rod 27 by means of a hand lever 28. By means ofsaid high pressure pump'26, pressure is supplied to thepistoncylinder-arrangement 16, 17 such that the head 12 of the polishrod is brought out of contact with the plate 13, linking thepistoneig'ylinder-arrangement 16, 17 into the force transmission i iathand the pressure of the pressure fluid within the cy lnder 17 is anexact measure for the load of the polish rod 10. A load diagram can berecorded, for instance on a drum-recorder or the like, as showngenerally at 60.

By opening the release valve 29 the piston-cylinderarrangement 16, 17 isset free and can then be removed.

FIGURE 4 shows the spring-loaded piston rod 19, the lever 20 and thedisengaging lever 21 in greater detail. The low pressure cylinder 18 isformed by a sleeve 30 inserted into a bore of the dynamometer body 31and sealed thereto by a sealing ring 32. Within the low pressurecylinder 18 a piston 33 is slidably mounted, said piston being connectedto the piston rod 19, which in turn is urged by means of a compressionspring 34 towards the left-hand end of the cylinder 18. The spring 34abuts with its one end against the rear end of the piston 33 and withits other end against a shoulder 45 of a bore 36 of a member 37 fastenedto the dynamometer body 31 by means, not shown, for instance screw boltsor the like. Within the bore 36 the piston rod 19 is guided, said pistonrod on its upper face being provided with a rack 38 cooperating with apinion 39 rotatably mounted by means of an axle 40 within the member 37.Axle 40 is fixed to the lever 20, andlever 20 can be turned in thedirection of the double arrow 41.

The rear end of the piston rod 19 on its lower side has arecess 42 intowhich is engaged a nose 43 of a plate 44 pivotally mounted within a slot46 of the member 37 by means of a pin 45. This engaging lever 21 isfixed to plate 44, and plate 44 has a hole 47 into which engages the oneend of a compression spring 48, the other end of which engages with ahole 49 of a plate 50 screwed to the member 34. As shown in this figure,the device is in its tensioned and secured position with nose 43engaging recess 42. The lever 20 has been turned to its left-handposition so that the compression spring 34 is compressed. When it isdesired to release the device, the disengaging lever 21 is turned in thedirection of the arrow 51 so that the nose 43 slides ofi? the recess 42.When the piston rod 19 is released, the piston 33 is forced by thespring 34 towards the left-hand end of the cylinder, so that thehydraulic fluid contained in the cylinder 18 is forced out throughconduit 22. When the piston 33 moves to the left, the lever 20 is turnedin a clockwise direction about the axle 40.

If it is desired to retension the device, the lever 20 is turned in acounter-clockwise direction, so that the pinion 39 is rotated movingpiston rod 19 to the right as shown in FIGURE 4, thereby retensioningthe spring 34. When the piston 33 has reached the position shown inFIGURE 4, nose 43 can enter into recess 42 holding rod 19 in theposition shown in FIGURE 4.

I claim:

1. In a dynamometer comprising a hydraulic pressure unit including acylinder means and a piston means adapted to reciprocate in saidcylinder means and a pressure recording means operatively connected withsaid hydraulic pressure unit, said hydraulic pressure unit being adaptedto be interposed in the force transmission path, which is defined by agenerally vertically reciprocating pump rod of a deep well pump, saidpump rod being operatively carried by a first cross-head memberconnected to said deep well pump, said pump rod having in addition asecond cross-head member longitudinally spaced from said firstcross-head member in the direction of travel of said pump rod, saidpiston means and said cylinder means being interposed between said firstand second cross-head members, the improvement comprising:

a low-pressure, high-displacement pump, communicating with said cylindermeans for hydraulically driving said piston means into extension fromsaid cylinder means and into engagement with one of said cross-headmembers after said cylinder means is placed in an abutting relationshipwith the other of said cross-head members, a high-pressure,low-displacement pump communicating with said cylinder means forhydraulically further extending said piston means thereby separatingsaid cross-head members and causing the force on said pump rod to betransmitted to said first cross-head member through said piston means,and means for selectively actuating said low pressure and high pressurepump.

2. The dynamometer defined in claim 1 wherein said low pressure pumpcomprises a second cylinder and piston means, and additionally comprisesa compression spring connected to said second piston means andreleasable means for holding said spring in a compressed state untilreleased whereupon said spring will displace said second piston and willoperatively displace said piston positioned between said firstcross-head member and said second cross-head member.

3. The dynamometer defined in claim 1 additionally including a checkvalve between said low-pressure pump means and said cylinder means, saidcheck valve opening in the direction of said cylinder means.

References Cited UNITED STATES PATENTS 3,004,426 10/1961 Lodynski 73-1412,741,915 4/1956 Renken et al. 73-151 X CHARLES A. RUEHL, PrimaryExaminer US. Cl. X.R. 73-151

